1. Field of the Invention
The present invention relates generally to methods and devices for loading cans in synchronous, high speed operations from starwheels onto corresponding aligned mandrels for processing of the cylindrical article, and more particularly pertains to a method and device involving selectively activated gas jets to axially urge a cylindrical article from a starwheel pocket onto a mandrel and, preferably, further includes a vacuum source connectable at preselected positions to a passage through the mandrel to cooperate with the gas jet in feeding the cylindrical article onto the mandrel for processing.
2. Description of the Prior Art
There exists a substantial background of art dealing with processing of cylindrical articles, and particularly of cans closed at one end and open at the other end, by means of mounting the can on a mandrel and performing the desired process. Among the processes commonly practiced are trimming a cam to a desired length, paneling of the can, flanging of the can, beading the edge of a can and other such well-known operations.
In order to facilitate high speed processing which often is carried out at rates of 600 to 800 cans per minute, a more or less conventional approach has been derived. Generally, the can is first placed in a rotatable starwheel pocket, either through conventional tangential feed, or through axial feed as disclosed in, for instance, copending U.S. Patent application Ser. No. 612,159, now U.S. Pat. No. 4,014,228. The starwheel may move in an indexed fashion, i.e., through such a Geneva drive mechanism which, in essence, intermittantly starts and stops the starwheel. The indexing drive facilitates feeding and movement of the can axially onto a mandrel for processing. However, preferably the starwheel is driven in a continuous fashion to facilitate high speed operation. A plurality of mandrels are synchronously driven adjacent to but axially spaced from the starwheel with a mandrel aligned with each pocket of the starwheel. Thus, whether driven in an indexing fashion or continuously, the pocket and mandrel are maintained in axial alignment.
The instant invention pertains most particularly to the axial movement of the cylindrical article from the starwheel pocket onto the mandrel. While this is a simple motion per se, high speed operation of the apparatus and attendant timing requirements and kinetic energies are troublesome, particularly with regard to jamming. If for some reason the mechanism or a can becomes jammed, the rapidly rotating starwheel and mandrel may be severely damaged.
Heretofore, axial movement of the cylindrical article from the starwheel pocket onto the mandrel has been accomplished by various means. However, most prior art devices involved axial movement of a mechanical member into the starwheel pocket to displace the cylindrical article onto the mandrel. The presence of an axial moving mechanical member in the starwheel pocket further comprised trouble free operation. While the cylindrical articles, and particularly thin wall aluminum or steel wall cans, are relatively lightweight and structurally weak, the mechanical feed mechanism moving with close time and space tolerances can be easily jammed by even a lightweight article.
Examples of various axial feed mechanisms may be found, for instance, in copending Dean U.S. patent application Ser. No. 612,159 for "METHOD AND APPARATUS FOR TRIMMING CYLINDRICAL ARTICLES," now U.S. Pat. No. 4,014,228, Maytag U.S. Pat. No. 3,425,251 and Larken et al. U.S. Pat. No. 3,838,653. In these prior approaches, a ram member is axially displaced into the starwheel pocket to physically push the can onto a corresponding mandrel. After the process is accomplished, the can may be ejected from the mandrel by a compressed air blast within the can to urge it back into the starwheel pockets.
Windstrup U.S. Pat. No. 3,548,769 employes a somewhat different approach with an indexing movement. However, again a mechanical pusher displaces the can from a starwheel pocket onto a corresponding mandrel, and a mechanical strip mechanism removes the can from the mandrel.
A particularly popular infeed approach involves the provision of a cup communicating with a vacuum source on a pusher arm which moves into the starwheel pocket. The vacuum in conjunction with the cup engages the closed end of the cylindrical artivcle and holds it securely by means of the vacuum while axial movement and processing is accomplished. Examples of such prior art apparatus employing this approach are to be found in Armbruster et al. U.S. Pat. No. 3,400,620; Cvacho et al. U.S. Pat. No. 3,756,103, Paramonoff U.S. Pat. No. 3,802,364; Langewis U.S. Pat. No. 3,802,363; Paramonoff U.S. Pat. No. 3,839,933 and Langewis U.S. Pat. No. 3,864,995.
The above specified prior art, as a whole, displays a highly developed system for can trimming utilizing rotary movement of a starwheel and corresponding mandrels carried on a rotating support with both indexing and continuous movement. However, in most every instance, a complex system for axially moving a mechanical feed member into the starwheel with attendant dangers of mistiming, jamming and damage to the apparatus is to be found.